Hydrofracturing, commonly known as hydraulic fracturing or fracking, is a method of increasing the flow of oil, gas, or other fluids into a well-bore from the surrounding rock formation. Hydrofracturing involves pumping a fracturing liquid into the well-bore under high pressure such that fractures form in the rock formation surrounding the well-bore through which oil and gas can flow into the well-bore and thus, be recovered. However, during recovery, the pressure inside the well-bore, or against the fracture walls, is lower than the pressure applied through the fracturing liquid when forming the fractures. As fractures are formed through high pressure forces rather than through drilling, which involves the removal of mass, fractures are more susceptible to closure due to natural tendency and the forces applied by the surrounding formation.
In order to keep the fractures open during recovery, proppant is placed in the fractures. Proppants are solid particles, commonly ranging from 0.5-2 mm, which are injected into the fractures to prop the fractures open while allowing fluid to flow through its interstitial space. Proppants are commonly mixed into fracturing fluid and injected into the fractures with the fracturing fluid as the fractures are created.
Traditionally, proppants are made from raw materials such as Brady and Ottawa White sands, kaolin, and bauxite. However, due to increasing application of hydrofracturing and thus demand for proppant, the cost of such conventional raw materials is rapidly increasing.